Variable opening die bolster for extrusion press

ABSTRACT

In a press for effecting extrusion of metals such as aluminum, having an extrusion die carried by a tool container, there is provided a die-supporting bolster dimensioned to fit within the tool container in abutting relation to the outlet face of the die and including a pair of gates movable toward and away from each other transversely of the direction of extrusion to define an opening of variable size in register with the die aperture. The gates are supported in the bolster by suitable means for effecting such movement; as one example of gate-moving means, the gates may be threadedly mounted on a pair of rotatable rods which extend in the direction of gate movement on opposite sides of the gates and are journaled in a rigid frame portion of the bolster. In this embodiment, each rod bears two oppositely directed threaded portions respectively engaging the two gates so that rotation of the rods effects oppositely directed movement of the gates, the rods being interconnected for simultaneous rotary movement upon application of rotary drive to one of them by suitable means such as, for example, an external drive shaft. The bolster is used to support a compound die which includes a major die having an aperture and a minor die received in a recess in the major die to define a smaller aperture, for producing a stepped extrusion having a first portion of cross section formed by the minor die and a second portion of larger cross section formed by the major die. In such operation, the bolster gates are initially closed sufficiently to hold the minor die in place and are moved apart by rotation of the rods after the first portion of the extrusion has been formed to release the minor die while retaining the major die in position to form the second portion of the extrusion.

United States Patent n 13,5ss,s34

[72] Inventors Jan Leon De Bruyn;

Jakob Lou; Charles Stanely Mitchell; Harold lner Wise, all of Kingston,Ontario, Canada [21] Appl. No. 733,886 [22] Filed June 3, 1968 [45]Patented June 22, 1971 {73] Assignee Alcon Research and DevelopmentLimited Montreal, Quebec, Canada [54] VARIABLE OPENING DIE BOLSTER FOREXTRUSION PRESS 6 Claims, 11 Drawing Figs.

[52] US. Cl 72/260, 72/468 [51] int. C1 ..B2lc 25/08, B2 1 j 13/00 [50]Field otSearch 72/253, 260, 468

[56] References Cited UNITED STATES PATENTS 2,7 I 5,459 8/1955 Krause72/260 3,165,141 l/1965 Tishken..... 72/468 899,518 9/1908 Edwards72/468 FOREIGN PATENTS 565,608 1 1/1958 Canada 72/260 544,1 14 3/1942Great'Britain 72/260 Primary Examiner-Charles W. Lanham AssistantExaminer-Robert M. Rogers Attorneys-Robert S. Dunham, P. E. Henninger,Lester W. Clark, Gerald W. Griffin, Thomas F. Moran, Howard J.Churchill, R. Bradlee Boal and Christopher C. Dunham ABSTRACT: In apress for effecting extrusion of metals such as aluminum, having anextrusion die carried by a tool container, there is provided adie-supporting bolster dimensioned to fit within the tool container inabutting relation to the outlet face of the die and including a pair ofgates movable toward and away from each other transversely of thedirection of extrusion to define an opening of variable size in registerwith the die aperture. The gates are supported in the bolster bysuitable means for effecting such movement; as one example ofgate-moving means, the gates may be threadedly mounted on a pair ofrotatable rods which extend in the direction of gate movement onopposite sides of the gates and are journaled in a rigid frame portionof the bolster. In this embodiment, each rod bears two oppositelydirected threaded portions respectively engaging the two gates so thatrotation of the rods effects oppositely directed movement of the gates,the rods being interconnected for simultaneous rotary movement uponapplication of rotary drive to one of them by suitable means such as,for example, an external drive shaft. The bolster is used to support acompound die which includes a major die having an aperture and a minordie received in a recess in the major die to define a smaller aperture,for producing a stepped extrusion having a first portion of crosssection fon'ned by the minor die and a second portion of larger crosssection formed by the major die. In such operation, the bolster gatesare initially closed sufficiently to hold the minor die in place and aremoved apart by rotation of the rods after the first portion of theextrusion has been formed to release the minor die while retaining themajor die in position to form the second portion of the extrusion.

PATENTED JUN22|97| 35 5,5334

sum 2 OF 4 PATENTEU JUN 22 |97l SHEET '4 BF 4 VARIABLE OPENING DIEBOLSTER FOR EXTRUSION PRESS BACKGROUND OF THE INVENTION This inventionrelates to apparatus for effecting extrusion of metals and the like, andparticularly to elements for supporting dies in extrusion presses. In aspecific sense, it is directed to devices, for supporting compound diesof the type comprising a major die having an aperture and a minor diereceived within a recess in the major die to define a smaller aperturein register with the major die aperture, arranged and adapted to efi'ectrelease of the minor die at a desired point in the extrusion of anarticle so that first and second portions of the article have crosssections respectively formed by the minor and major dies.

For purposes of illustration, particular reference will be made hereinto aluminum as an example of a metal suitable for extrusion in apparatusincorporating the die-supporting element of the present invention. I

In a conventional direct extrusion press for producing extruded aluminumarticles, a heated aluminum ingot in an ingot container is forced by ahydraulically or mechanically actuated ram through a die positioned atone end of the ingot container. The die, and one or more supportingelements disposed on its outlet side to hold the die in position againstmovement in the direction of extrusion when extruding pressure isapplied to the ingot, are carried in a removable tool containerinterposed between the ingot container and a fixed platen and surroundedby suitable housing structure. In assembly of the press for operation,the die and bolsters are placed in the tool container, which is theninserted into the press either axially through the platen opening (in agate lock press) or laterally across the face of the platen (in a dieslide press); thereafter, the outlet end of the ingot container isbrought into sealing contact with the die and the extrusion operationbegins.

Continuous, integral extruded aluminum articles having a first portionof one cross section and a second portion of different and larger crosssection are produced in present-day commercial practice for a variety ofpurposes. In the formation of such an article (commonly tenned a steppedextrusion) in an extrusion press, the first portion of the article isextruded through a first die aperture conforming to the desired crosssection of such first portion, and after the die aperture is changed(while the unextruded portion of the ingot remains in the ingotcontainer), the second portion of the article is extruded, i.e. througha second die aperture conforming to the desired second-portion crosssection.

One known procedure for producing stepped extrusions in conventionaldirect extrusion presses employs two separate dies, respectively havingapertures shaped to form the first and second portions of the article.The press is initially assembled with the smaller aperture die in thetool container; after the first portion of the article has been extrudedthe initial die is replaced with the larger aperture die. In a gate-lockpress, such changing of dies requires removal of the tool container fromits operative position in the press, while in a die-slide press, theingot container is displaced away from the slide to enable the die to bechanged. Satisfactory stepped extrusions can be produced in this way,using conventional press equipment, but the withdrawal of the toolcontainer or the ingot container in order to change the dies isinconvenient and necessitates an extended interruption of the extrudingoperation.

It has been proposed to employ a compound die including a major diewhich has an aperture conforming to the desired cross section of thesecond portion of the extrusion and a minor die fitted into a recess inthe major die to define a smaller aperture conforming to the desiredcross section of the first portion of the extrusion. During extrusion ofthe first portion of the article, both the major die and the minor dieare supported against movement in the direction of extrusion, but uponcompletion of the first portion, the die-supporting arrangement of thepress is changed so that only the major die is supported against suchmovement; thus, when the extruding operation is resumed, the minor dieis advanced from the recess along with the article being extruded, andthe second portion of the article is formed by the aperture of the majordie.

In some instances of operation using a compound die, the die supportduring the first portion of the extrusion is provided by a bolsterabutting the outlet face of the die and having an aperture (for passageof the extruded article) small enough to prevent displacement of theminor die under extruding pressure. After the first portion of thearticle is formed, this bolster is replaced with a second bolster havingan aperture sufficiently large to permit release of the minor die fromthe recess. As in the case of use of separate dies, changing of thebolster involves removal of the tool container from the press (ordisplacement of the ingot container) and thus necessitates anoperationally inconvenient and time-consuming interruption in theextruding procedure.

Alternatively, it has further been proposed to provide (in place of theusual tool container) a so-called secondary locking frame comprising apair of gates, disposed in abutting relation to the outlet face of thedie and movable toward and away from each other by suitable hydraulicmeans, the directions of gate movement being perpendicular to thedirection of extrusion. The gates are initially closed sufficiently tohold the minor die in place, but are opened after the first portion ofthe article has been extruded to release the' minor die while retainingthe major die in place. Use of these gates obviates the necessity forwithdrawing the tool container to change the die aperture and thusexpedites the production of a stepped extrusion; however, the provisionof the hydraulically operated gate structure requires substantial andexpensive modification of the press, including substitution of specialtool containers for the conventional tool container.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a new and improved device for supporting a compound major andminor die, enabling production of a stepped extrusion in a conventionalextrusion press without structural modification of the press and withoutrequiring removal of the tool container or displacement of the ingotcontainer at an intermediate stage in the extruding operation to changethe size of the die aperture.

To this and other ends the present invention broadly contemplates theprovision of a die-supporting bolster comprising, in combination, arigid frame dimensioned to fit within a conventional extrusion presstool container in abutting relation to the outlet face of a die held inthe container, and adapted to withstand extrusion pressure transmittedby the die in the direction of extrusion; at least one gate mounted inthe frame and cooperating therewith to define an opening in registerwith an aperture of the die, this gate having one face extendingtransversely of the direction of extrusion and positioned to abut theoutlet face of the die when the frame is disposed in abutting relationthereto, the gate being immovable relative to the frame in the directionof extrusion but being movable within the frame in a directiontransverse to the extruding direction for varying the size of theopening; and means accessible from the exterior of the tool containerfor moving the gate and maintaining the gate fixedly in any position towhich it is moved.

In a particular embodiment of the invention, the bolster structureincludes a pair of gates, both abutting the outlet face of the die andmovable toward and away from each other in the bolster frametransversely of the direction of extrusion to define the aforementionedopening of the bolster. The gatemoving means effects simultaneousmovement of both gates toward or away from each other, and holds bothgates fixedly in any position to which they are moved.

Various forms of gate-moving means may be employed in this embodiment.One advantageously simple and effective gate-moving means, constitutinga further particular feature of the invention is a specific aspectthereof, includes a pair of externally threaded rods rotatably journaledin the bolster frame and extending, in parallel relation to thedirection of gate movement and at opposite sides of the gates, throughinternally threaded bores formed in side portions of the gates. Each ofthe rods has two oppositely directed threaded portions respectivelyengaging correspondingly threaded bores of the two gates; thus, rotationof the rods effects the desired simultaneous movement of the gatestoward or away from each other. When the rods are stationary, the gatesare held fixed in any position to which they have been moved by thethreaded engagement of their bores with the rods.

One of the rods is disposed and arranged to be accessible for engagementby suitable means (such as an external drive shaft) to impartgate-moving rotary motion to the rods when the described bolster is inoperative position in an extrusion press tool container. Further, thetwo rods are interconnected to that both rods rotate together when theexternally accessible rod is driven. In this way, the gates may beopened or closed (i.e. the size of the opening defined between them maybe varied) while the bolster remains in position in the tool containerwith the tool container positioned in the press.

In use with a compound die including major and minor die components asdescribed above, the bolster is disposed in dieengaging position in thetool container and the tool container is placed in operative position inthe press. Initially, the bolster gates are closed sufficiently toretain the minor die within the recess of the major die so that duringthe first portion of the extruding operation the cross section of theextruded article is formed by the aperture of the minor die. When it isdesired to change the aperture size for extrusion of the second portionof a stepped extruded article, the extruding pressure on the toolcontainer is temporarily relieved and the bolster rods are rotated bymeans of the external drive shaft to open the bolster gates far enoughto release the minor die. Extrusion is then resumed, and as the extrudedarticle advances through and beyond the die it carries with it the minordie (now no longer restrained by the bolster), the second portion of theextruded article thus having a cross section formed by the aperture ofthe major die. Change in die aperture for production of a steppedextrusion is thus simply and quickly effected, by the describedadjustment in spacing of the bolster gates, without extended delay ordisassembly of the press. Owing to the fact that the bolster of theinvention is dimensioned to fit within a conventional tool container, nostructural modification of the press is required to provide thisoperation.

Further features and advantages of the invention will be apparent fromthe detailed description hereinbelow set forth, together with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a simplified sideelevational sectional view of a conventional gate lock-type directextrusion press as used for extrusion of aluminum articles,incorporating a bolster structure embodying the invention in aparticular form;

FIG. 2 is an exploded perspective view of a compound die including majorand minor die components as used. for production of a stepped extrusionin the press of FIG. I;

FIG. 3 is a fragmentary perspective view of a stepped extrusion producedby the die of FIG. 2;

FIG. 4! is an enlarged view, taken along the line 4-4 of FIG. I, of theembodiment of the invention shown in FIG. I;

FIG. 5 is a view, partly in section, taken along the line 5-5 of FIG. I;

FIG. 6 is an enlarged fragmentary plan view of the press of FIG. I,showing a conventional form of housing for the tool container of thatpress;

FIG. 7 is a fragmentary sectional view taken along the line 7-7 of FIG.6;

FIG. 8 is an enlarged elevational sectional view of the die, bolster andadjacent structures of the press of FIG. I, illustrating formation of afirst portion of a stepped extrusion with the minor die in place;

FIG 9 is a view similar to FIG. 6 illustrating formation of a secondportion of a stepped extrusion after release of the minor die;

FIG. I0 is a schematic perspective view of a conventional die slide-typedirect extrusion press, partially exploded and incorporating a bolsterdevice embodying the invention; and

FIG. II is a schematic perspective view of the press of FIG. I0 showingthe tool container in position during the later portion ofan extrudingoperation.

DETAILED DESCRIPTION Referring first to FIG. I, there is shown agenerally conventional gate lock-type direct extrusion press as used forextruding aluminum articles, including an ingot container It), a toolcontainer II supporting a die I2, and a fixed platen I4, disposed insuccessive relation along the path of extrusion. The ingot container hasa central cylindrical passage I6 holding an ingot I7 of aluminum to beextruded and receives the forward end of a hydraulically or mechanicallyactuated ram 19 which forces the ingot I7 through the aperture of die12, the head of the ram being conventionally spaced from the ingot by adummy block 20.

The tool container II includes at one end (adjacent to the ingotcontainer I0) an open semicylindrical die-holding portion 22 whichcontains the die I2, together with a bolster device 24 embodying thepresent invention (herein after further described) and one or moreconventional supplemental supporting bolsters 25 (herein termedsubbolsters) disposed in successive abutting relation along the path ofextrusion, each of these subbolsters having an opening aligned with thedie aperture and sufficiently large to permit passage of the extrudedarticle with clearance. A key 26 (shown in FIG. 4), convenientlyconstituted by a metal bar, is welded or screwed to and extends alongthe bottom inner surface of the tool container portion 22 to engage keyslots formed in the die and supporting elements so as to restrain themagainst angular displacement in the tool container. The portion of thetool container disposed forwardly of the subbolsters 25 in the directionof extrusion is a thick-walled rigid cylindrical head 27 having acentral passage for the extruded article, and against which the forwardone of the subbolsters 25 bears.

The platen I4 has an internal bore sufficiently large to permitinsertion of the tool container therethrough, i.e. axially of theplaten, for positioning of the tool container in its operative locationin the press. When the tool container is thus positioned, a yoke-shapedgate lock 29, hydraulically operated and displaceable in a directiontransverse to the direction of extrusion, is interposed between the toolcontainer II and the inlet end of platen I4 so that the outlet end ofthe tool container head 27 and the inlet end of the platen abut againstopposite sides of the gate lock. With this arrangement of elements,extruding pressure acting on the die I2 is transmitted successivelythrough the bolster device 24, the subbolsters 25 and the tool containerhead 27 to the gate lock and thence to the fixed platen Id, all theseelements being rigid structures having adequate strength to withstandsuch pressure and hence to support the die 12 against displacement inthe direction of extrusion.

As more particularly shown in FIG. 2, the die 112 includes a major die30 having an aperture 31 shaped to conform to the desiredcross-sectional configuration of the second (i.e. larger cross section)portion of a stepped extrusion to be produced in the press. Adjacent theoutlet face 32 of major die 30, the aperture 31 is enlarged to form arecess 34 dimensioned and adapted to receive a minor die 35 whichdefines an aperture 36 shaped to conform to the desired cross section ofthe first portion of the stepped extrusion. Minor die 35 mayconveniently be a composite die having three segments (designated 37, 38and 39) which, when assembled, together define the aperture 36. At itsinner end, the recess 34 has a shoulder M against which the segments ofthe minor die 35 bear when they are in position in the recess; when theminor die is thus positioned, its outlet face is coplanar with the backface of the major die 30. This compound die is adapted to form a steppedextrusion 43 of the shape shown in FIG. 3, having a first portion 45conforming in cross section to the minor die aperture 36 and a secondportion 46 conforming in cross section to the major die aperture 31.

As stated, with the exception of the bolster device 24 (now to bedescribed), the various elements referred to above may all be entirelyconventional in structure, arrangement and operation, and accordinglyneed not be described in detail.

Referring now to FIGS. 4 and 5, the device 24 there shown, embodying theinvention and adapted for use in the press of FIG. 1, includes a rigidbolster disc 50 having plane parallel opposed disc surfaces with acircular periphery shaped to conform to the internal cross-sectionalconfiguration of the tool container portion 22. A central aperture 52extends through the disc 50 between the opposed surfaces thereof, beingpositionedfor register with the die aperture when the device 24 isdisposed in the tool container, and dimensioned to accommodate withclearance an extruded article of any cross section that may be fomiedusing the device; specifically, the aperture 52 is larger in alldirections than the recess 34 of the major die 30, so as to permitpassage of the segments comprising the minor die 35 through and beyondthe disc 50. A slot 54 is formed in the lower edge of the disc 50 toengage the key 26 in the tool container for restraint of the discagainst angular displacement relative to the tool container.

Two vertically extending frame members 56 and 57 are mounted on one ofthe plane surfaces of disc 50 on opposite sides of the aperture 52 so asto define a vertical channel or slideway 58 extending essentially fromthe upper edge to the lower edge of the disc surface, across the openingof aperture 52 therein, this channel being wider than the recess 34 ofthe major die 30. The edge portions of members 56 and 57 adjacent to thechannel 58 are shaped to form vertical grooves (respectively designated59 and 60) coextensive with the channel and opening toward each otheracross the channel. The outer peripheral edges of the two frame membersare of arcuate configuration, conforming to the periphery of the disc 50so as to be receivable therewith in the tool container portion 22, andthe exposed major surfaces of these members (i.e. the surfaces facingaway from the disc 50) lie in a common plane which is perpendicular tothe direction of extrusion when the device 24 is disposed in the toolcontainer.

The disc 50 and members 56 and 57 (which are conveniently secured to thedisc by screws 62) together constitute a rigid bolster frame, beingfabricated of a suitable steel or like metal resistant to deformationunder extrusion pressure. The frame structure also includes a horizontalbar 63, extending across the upper extremity of the channel 58 above themembers 56 and 57 and secured to the upper ends of these members byscrews 65; as shown, the bar 63 is spaced above the members 56 and 57 byblocks 66 through which the screws 65 project, and bears a centrallydisposed sprocket chain guide block 68.

A pair of vertically movable gates, respectively designated 70 and 71(e.g. also fabricated of a suitable steel) are positioned one above theother within the channel 58 between the frame members 56 and 57. Each ofthese gates has plane opposed major surfaces, of which one isessentially contiguous to the adjacent plane surface of the disc 50 andthe other is coplanar with the exposed major surfaces of members 56 and57, both gates extending across substantially the entire width of thechannel 58. The gates are so arranged that the lower edge of the uppergate 70 and the upper edge of the lower gate 71 constitute the upper andlower edges, respectively, of an opening 73 which is in register withthe aperture 52 of disc 50 and which can be varied in vertical extent bymovement of the gates toward or away from each other within the channel.For-- A pair of sleeves 74, 75 each having an axially vertical,internally threaded bore are respectively welded to opposite side edgeportions of the upper gate and received in the grooves 59, 60 whichextend along the sides of the channel 58. A similar pair of sleeves 76,77, again with axially vertical, internally threaded bores, arerespectively welded to opposite side edge portions of the lower gate 71and received in grooves 59 and 60, the bores of sleeves 76 and 77 beingrespectively axially aligned with the bores of sleeves 74 and in thesegrooves. Through the bores of sleeves 74 and 76 of the two gates ingroove 59, there extends an axially vertical rod 78 having upper andlower externally threaded portions 79 and 80 respectively engaging theinternal threads of the upper and lower sleeve bores. A second axiallyvertical rod 82 extends through the bores of sleeves 75 and 77 in groove60 and has upper and lower externally threaded portions 83 and 84respectively engaging the internal threads of these two sleeve bores.Both rods are joumaled adjacent their upper extremities in thehorizontal bar 63, for rotation about their respective axes, and bearcollars 86 which act as stops to prevent vertical movement of the rodsrelative to the horizontal bar.

The upper threaded portions 79, 83 of the two rods, as likewise thebores of sleeves 74, 75 secured to the upper gate 70, bear threads whichare opposite in rotational sense to the threads of the lower threadedrod portions 80, 84 and the bores of the sleeves 76, 77 secured to thelower gate 71; i.e. if the upper rod portions and sleeve pores haveright-handed threads, the lower rod portions and sleeve bores havelefthanded threads. Consequently, simultaneous rotation of the two rods78 and 83 effects simultaneous but oppositely directed vertical movementof the gates 70 and 71 in channel 58, moving them toward or away fromeach other and thereby narrowing or widening the opening 73 definedbetween them. When the rods are stationary, their threaded engagementwith the gate sleeves holds the gates fixed in any position to which thegates have been moved.

Above the horizontal bar 63, each of the two rods 78 and 82 bears asprocket 88, the two sprockets being interconnected in conventionalmanner by a chain 89 (which passes around guide block 68) so that bothrods rotate simultaneously in the same direction upon application ofrotary drive to one of them. The upper extremity 90 of rod 82 is shapedto be engageable by a drive shaft for effecting rotation of this rod andsimultaneous rotation of rod 78 through the described chainand-sprocketarrangement; for example, the rod extremity 90 may be hexagonal (asshown) or square in cross section, for engagement with a drive shafthaving a correspondingly shaped hexagonal or square socket.

The upper gate 70 may bear an upwardly projecting indicator pin 91positioned in register with a vertical hole 910 extending through thebar 63 and guide block 68. When the gates are open, the pin 91 projectsthrough hole 91a to provide an externally visible indication of the opencondition of the gates.

In assembling the press of FIG. 1 for production of a stepped extrusionusing the device 24, the tool container 11 is withdrawn from the pressand the die 12, device 24 and additional subbolster or subbolsters 25are placed in the tool container portion 22 with the gates 70 and 71 ofthe device disposed in abutting relation to the outlet face of the die.As thus assembled, the die carries the minor die 35 positioned in therecess 34, and the gates 70 and 71 of device 24 are fully closed toretain the minor die in such position. The tool container is theninserted axially through the bore of platen 14 into its operativeposition in the press being there surrounded by conventional gatehousing structure 92, as shown in FIGS. 6 and 7), and the gate lock 29is lowered into position between the tool container and platen. When thetool container is in place, the upper extremity 90 of rod 82 is inregister with a small hole 94 formed in the gate housing 92.

Preparatory to the extruding operation, pressure is applied to the ingotcontainer to seal the outlet end of the ingot container against theinlet face of the die 12. With a suitably heated ingot I7 of aluminum(or aluminum alloy) disposed in the ingot container passage, the ram 19is actuated to exert extruding pressure on the ingot through dummy block20 and thus to force metal of the ingot forwardly through the dieaperture.

As particularly shown in FIG. 8, during the initial stage of theextruding operation the gates 70 and 71 of the device 24, being closed,abut the outlet faces of the segments comprising the minor die 35; thusthe minor die segments bear against the gates, transmitting extrudingpressure thereto, and are restrained against movement in the directionof extrusion. Consequently, the metal being extruded through the dietakes the cross-sectional shape of the minor die aperture 36 andadvances beyond the die, as a continuous extruded article portion 45having such cross section, through the opening between the gates 70 and71.

When a desired length of portion 45 has been extruded, the extrudingpressure is temporarily relieved, the ram 19 is retracted slightly (e.g.about 1 inch), the ingot container sealing pressure is removed, and theingot container is moved slightly (e.g., again, about 1 inch) away fromthe die 12. A drive shaft 96 (FIG. 7) having a suitably shapedhexagonalor square-holed) socket 97 is then inserted through the hole 94in the gate housing, into engagement with the correspondingly shaped(hexagonal or square) end 90 of rod 82. This drive shaft rotates the rod32 and also rotates the rod 73 through the chain and sprocket drive 88,89 in such direction as to effect opening of the gates 70 and 7H, i.e.to cause the gates to move apart, sufficiently to release the segmentscomprising the minor die 35. In other words, the spacing between thegates is thereby widened until the gates no longer abut the outlet faceof the minor die (although they still abut the outlet face of the majordie 30), the minor die segments being then free to pass between thegates in the direction of extrusion.

After the gates have been opened, the ingot container is again broughtforward into sealing engagement with the die inlet face and the ram isonce more actuated to continue the extruding operation. As extrusionresumes, the metal being extruded through the die carries the segmentsof minor die 35 forwardly with it through and beyond the open gates 70,7i (as shown in FIG. 9), which still retain the major die 34) againstmovement in the direction of extrusion. Accordingly, the portion of theextrusion formed after the gates are opened has a cross section shapedby the major die aperture 31, i.e. it constitutes the second portion atas shown in FIG. 3. When the required length of this second portion 66has been extruded, the remaining butt of ingot 17 in the tool containeris ejected and sheared off in accordance with conventional procedure.

By the described use of the device of the present invention, acontinuous stepped extrusion having first and second portions differingfrom each other in cross section may by rapidly and easily produced. Inparticular, the necessary change in die aperture is effected at thedesired time in an advantageously facile manner, without extended delayor interruption of the extruding operation as would be required if thetool container had to be withdrawn from the press for such change. Atthe same time, owing to the fact that the device 24 fits wholly within aconventional tool container as well as being operable in situ, nostructural change or modification of a conventional gate lock press isnecessary to achieve these advantages, apart from the cutting of thesmall access hole 9d in the gate housing 92 to admit the drive shaft 96for opening the gates.

While the device of the invention has been described above as employedin a gate lock press, it may also be used in production of steppedextrusions in other types of conventional direct extrusion presses,again without requiring modification of the press structure. Forexample, as shown in FIGS. and ill, it may be used in a so-called dieslide press wherein the tool container is inserted laterally between thebillet container and platen.

The press of FIGS. 110 and H is generally similar to that of FIG. ll,i.e. including an ingot container 110 for holding a heated aluminumingot H7 which is extruded by means of a ram 19 through a die 12 whichmay comprise a major die 30 and minor die 35 received in a recess on theoutlet face of the major die. This die, together with the device 24 andone or more supporting subbolsters 25, are held in a tool container 98which as stated (and as particularly indicated in FIG. 10) is insertedlaterally between the ingot container and a platen 99. The operation ofthe device 24 in the press of FIGS, 10 and 11K is as described abovewith reference to the FIG. I press; ie. the gates 70 and 71 areinitially closed, to retain the minor die 35 in position so that thefirst portion 45 of the extruded article has a cross section formed bythe minor die aperture, and the gates are then opened (by rotation ofthe rods 78 and 82) to release the minor die so that the remainder ofthe extrusion has a cross section formed by the major die aperture.Since the tool container in a die slide press is not surrounded by gatehousing structure, the upper extremity of rod 82 is readily accessibleand may be turned (for opening the gates) by means such as a ratchetwrench.

It is to be understood that the invention is not limited to the featuresand embodiments hereinabove specifically set forth, but may be carriedout in other ways without departure from its spirit.

We claim:

I. A variable-opening bolster for use in an extrusion press having atool container arranged and adapted to hold an extrusion die andsupporting elements for maintaining said die fixed in position duringextrusion of an article therethrough, said bolster comprising, incombination,

a. a rigid frame dimensioned to fit within said tool container inabutting relation to the outlet face of said die and adapted towithstand extrusion pressure transmitted by said die in the direction ofextrusion of said article;

b. first and second gates mounted in said frame and cooperatingtherewith to define an opening in register with an aperture of said die,said gates having facing edges constituting opposite edges of saidopening, each of said gates having one face extending transversely ofthe direction of extrusion and positioned to abut said outlet face ofsaid die when said frame is disposed in abutting relation thereto, saidgates being immovable relative to said frame in the direction ofextrusion but being movable within said frame toward and away from eachother in a direction transverse to the direction of extrusion forvarying the size of said opening, each of said gates having, in a sideportion thereof, an internally threaded bore extending in the directionof movement of said gates, the bore of said first gate being axiallyaligned with the bore of said second gate and having an internal threadopposite in rotational sense to the internal thread of the bore of saidsecond gate; and

c. means accessible from the exterior of said tool container forsimultaneously moving said first and second gates as aforesaid inopposite directions and retaining said gates fixedly in any position towhich said gates are moved, said gate-moving means including at leastone rod rotatably journaled in said frame and extending through the boreof said first gate and the bore of said second gate aligned therewith,said rod having first and second externally threaded portionsrespectively engaging the internal threads of said bores, the externalthread of each of said rod portions corresponding in rotational sense tothe internal thread it engages, so that rotation of said rod effectssimultaneous oppositely directed translational movement of said firstand second gates.

2. A bolster as defined in claim l, wherein each of said gates has, inopposite side portions thereof, two internally threaded bores bothextending in the direction of movement of said gates, the bores of saidfirst gate being axially aligned with the bores of said second gate andhaving internal threads opposite in rotational sense to the internalthreads of the bores of said second gate; and wherein said gate-movingmeans comprises a pair of rods rotatably joumaled in said frame, each ofsaid rods extending through one of the bores of said first gate andthrough the bore of said second gate aligned therewith, each of saidrods having two externally threaded portions respectively engaging theinternal threads of the two bores through which it extends, the externalthread of each of said rod portions corresponding in rotational sense tothe internal thread it engages, so that rotation of said rods effectssimultaneous oppositely directed translational movement of said firstand second gates.

3. A bolster as defined in claim 2, wherein one of said rods has an endportion projecting above said frame for access from the exterior of saidtool container, said rod end portion being shaped for engagement withmeans for effecting rotation of said one rod, and wherein saidgate-moving means further includes means interconnecting said pair ofrods for transmitting rotary motion for said one rod to the other ofsaid rods.

4. In an extrusion press having a tool container arranged and adapted tohold an extrusion die and supporting elements for maintaining said diefixed in position during extrusion of an article therethrough, thecombination, with die structure disposed in said tool container andincluding a major die having a first die aperture enlarged on the outletface of said major die to form a recess and a minor die positionedwithin said recess to define a second die aperture in register with butsmaller than said first aperture, of a device for selectively preventingand permitting movement of said minor die from said recess duringextrusion of an article through said die structure, said devicecomprising:

a. a rigid frame disposed within said tool container and including apair of frame members positioned in abutting relation to the outlet faceof said major die and on opposite sides of said recess to define achannel wider than said recess and extending transversely of thedirection of extrusion of said article, each of said frame membershaving an edge portion adjacent said channel defining a groove extendingalong and opening into said channel, said frame being adapted towithstand extrusion pressure transmitted by said die in the direction ofextrusion of said article;

b. first and second gates disposed in said channel and cooperating withsaid frame members to define an opening in register with said recess,said gates having facing edges constituting opposite edges of saidopening, each of said gates having one face extending transversely ofthe direction of extrusion and abutting the outlet face of said majordie, said gates being immovable relative to said frame in the directionof extrusion but being movable toward and away from each other withinsaid channel for varying the size of said opening from a minimum size atwhich said gates abut the outlet face of said minor die to a maximumsize greater than said recess, each of said gates having two sleeveportions respectively disposed on opposite sides thereof and received insaid grooves of said frame members, each of said sleeve portions havingan internally threaded bore extending in the direction of movement ofsaid gates, the bores of said first gate being axially aligned with thebores of said second gate and having internal threads opposite inrotational sense to the internal threads of the bores of said secondgate; and

c. means for moving said gates within said channel, said meanscomprising i. a pair of rods rotatably journaled in said frame, each ofsaid rods extending through one of the bores of said first gate andthrough the bore of said second gate aligned therewith each of said rodshaving two externally threaded portions respectively engaging theinternal threads of the two bores through which it extends, the externalthread of each of said rod portions corresponding in rotational sense tothe internal thread it engages, so that rotation of said rods effectssimultaneous oppositely directed translational movement of said firstand second gates in said channel, one of said rods having an end portionaccessible from the exterior of said tool container for engagement bymeans for rotating said one rod; and

ii. means interconnecting said pair of rods for transmitting rotarymotion from said one rod to the other of said rods.

5. A deviceas defined in claim 4, wherein said frame further includes arigid bolster disc disposed in said tool container on the side of saidframe members remote from said die structure and secured to said framemember for supporting said frame members in fixed position, said bolsterdisc having an aperture, in register with but larger than said recess ofsaid major die, opening into said channel.

6. An extrusion press including a. a tool container arranged and adaptedto hold an extrusion die and at least one supporting element formaintaining said die fixed in position during extrusion of an articletherethrough in a given direction, said tool container having side andbottom wall portions extending from said die in said given direction andforming a receptacle for receiving and holding said die and said onesupporting element against displacement laterally of said givendirection; and

b. means disposed beyond said one supporting element in said givendirection for restraining said one supporting element againstdisplacement in said given direction; wherein the improvement comprises:

. a variable-opening bolster constituting said one supporting elementand removably received within said receptacle, said bolster comprising,in combination,

i. a rigid frame dimensioned to fit within said receptacle of said toolcontainer in abutting relation to the outlet face of said die andadapted to withstand extrusion pressure transmitted by said die in thedirection of extrusion of said article;

ii. first and second gates mounted in said frame and cooperatingtherewith to define an opening in register with an aperture of said die,said gates having facing edges constituting opposite edges of saidopening, each of said gates having one face extending transversely ofthe direction of extrusion and positioned to abut said outlet face ofsaid die when said frame is disposed in abutting relation thereto, saidgates being immovable relative to said frame in the direction ofextrusion but being movable within said frame toward and away from eachother in a direction transverse to the direction of extrusion forvarying the size of said opening, each of said gates having, in a sideportion thereof, an internally threaded bore extending in the directionof movement of said gates, the bore of said first gate being axiallyaligned with the bore of said second gate and having an internal threadopposite in rotational sense to the internal thread of the bore of saidsecond gate; and

iii. means accessible from the exterior of said tool container forsimultaneously moving said first and second gates as aforesaid inopposite directions and retaining said gates fixedly in any position towhich said gates are moved, said gate-moving means including at leastone rod rotatably journaled in said frame and extending through the boreof said first gate and the bore of said second gate aligned therewith,said rod having first and second externally threaded portionsrespectively engaging the internal threads of said bores, the externalthread of each of said rod portions corresponding in rotational sense tothe internal thread it engages, so that rotation of said rod effectssimultaneous oppositely directed translational movement of said firstand second gates.

1. A variable-opening bolster for use in an extrusion press having atool container arranged and adapted to hold an extrusion die andsupporting elements for maintaining said die fixed in position duringextrusion of an article therethrough, said bolster comprising, incombination, a. a rigid frame dimensioned to fit within said toolcontainer in abutting relation to the outlet face of said die andadapted to withstand extrusion pressure transmitted by said die in thedirection of extrusion of said article; b. first and second gatesmounted in said frame and cooperating therewith to define an opening inregister with an aperture of said die, said gates having facing edgesconstituting opposite edges of said opening, each of said gates havingone face extending transversely of the direction of extrusion andpositioned to abut said outlet face of said die when said frame isdisposed in abutting relation thereto, said gates being immovablerelative to said frame in the direction of extrusion but being movablewithin said frame toward and away from each other in a directiontransverse to the direction of extrusion for varying the size of saidopening, each of said gates having, in a side portion thereof, aninternally threaded bore extending in the direction of movement of saidgates, the bore of said first gate being axially aligned with the boreof said second gate and having an internal thread opposite in rotationalsense to the internal thread of the bore of said second gate; and c.means accessible from the exterior of said tool container forsimultaneously moving said first and second gates as aforesaid inopposite directions and retaining said gates fixedly in any position towhich said gates are moved, said gate-moving means including at leastone rod rotatably journaled in said frame and extending through the boreof said first gate and the bore of said second gate aligned therewith,said rod having first and second externally threaded portionsrespectively engaging the internal threads of said bores, the externalthread of each of said rod portions corresponding in rotational sense tothe internal thread it engages, so that rotation of said rod effectssimultaneous oppositely directed translational movement of said firstand second gates.
 2. A bolster as defined in claim 1, wherein each ofsaid gates has, in opposite side portiOns thereof, two internallythreaded bores both extending in the direction of movement of saidgates, the bores of said first gate being axially aligned with the boresof said second gate and having internal threads opposite in rotationalsense to the internal threads of the bores of said second gate; andwherein said gate-moving means comprises a pair of rods rotatablyjournaled in said frame, each of said rods extending through one of thebores of said first gate and through the bore of said second gatealigned therewith, each of said rods having two externally threadedportions respectively engaging the internal threads of the two boresthrough which it extends, the external thread of each of said rodportions corresponding in rotational sense to the internal thread itengages, so that rotation of said rods effects simultaneous oppositelydirected translational movement of said first and second gates.
 3. Abolster as defined in claim 2, wherein one of said rods has an endportion projecting above said frame for access from the exterior of saidtool container, said rod end portion being shaped for engagement withmeans for effecting rotation of said one rod, and wherein saidgate-moving means further includes means interconnecting said pair ofrods for transmitting rotary motion for said one rod to the other ofsaid rods.
 4. In an extrusion press having a tool container arranged andadapted to hold an extrusion die and supporting elements for maintainingsaid die fixed in position during extrusion of an article therethrough,the combination, with die structure disposed in said tool container andincluding a major die having a first die aperture enlarged on the outletface of said major die to form a recess and a minor die positionedwithin said recess to define a second die aperture in register with butsmaller than said first aperture, of a device for selectively preventingand permitting movement of said minor die from said recess duringextrusion of an article through said die structure, said devicecomprising: a. a rigid frame disposed within said tool container andincluding a pair of frame members positioned in abutting relation to theoutlet face of said major die and on opposite sides of said recess todefine a channel wider than said recess and extending transversely ofthe direction of extrusion of said article, each of said frame membershaving an edge portion adjacent said channel defining a groove extendingalong and opening into said channel, said frame being adapted towithstand extrusion pressure transmitted by said die in the direction ofextrusion of said article; b. first and second gates disposed in saidchannel and cooperating with said frame members to define an opening inregister with said recess, said gates having facing edges constitutingopposite edges of said opening, each of said gates having one faceextending transversely of the direction of extrusion and abutting theoutlet face of said major die, said gates being immovable relative tosaid frame in the direction of extrusion but being movable toward andaway from each other within said channel for varying the size of saidopening from a minimum size at which said gates abut the outlet face ofsaid minor die to a maximum size greater than said recess, each of saidgates having two sleeve portions respectively disposed on opposite sidesthereof and received in said grooves of said frame members, each of saidsleeve portions having an internally threaded bore extending in thedirection of movement of said gates, the bores of said first gate beingaxially aligned with the bores of said second gate and having internalthreads opposite in rotational sense to the internal threads of thebores of said second gate; and c. means for moving said gates withinsaid channel, said means comprising i. a pair of rods rotatablyjournaled in said frame, each of said rods extending through one of thebores of said first gate and through the bore of said second gatealigned therewith eAch of said rods having two externally threadedportions respectively engaging the internal threads of the two boresthrough which it extends, the external thread of each of said rodportions corresponding in rotational sense to the internal thread itengages, so that rotation of said rods effects simultaneous oppositelydirected translational movement of said first and second gates in saidchannel, one of said rods having an end portion accessible from theexterior of said tool container for engagement by means for rotatingsaid one rod; and ii. means interconnecting said pair of rods fortransmitting rotary motion from said one rod to the other of said rods.5. A device as defined in claim 4, wherein said frame further includes arigid bolster disc disposed in said tool container on the side of saidframe members remote from said die structure and secured to said framemember for supporting said frame members in fixed position, said bolsterdisc having an aperture, in register with but larger than said recess ofsaid major die, opening into said channel.
 6. An extrusion pressincluding a. a tool container arranged and adapted to hold an extrusiondie and at least one supporting element for maintaining said die fixedin position during extrusion of an article therethrough in a givendirection, said tool container having side and bottom wall portionsextending from said die in said given direction and forming a receptaclefor receiving and holding said die and said one supporting elementagainst displacement laterally of said given direction; and b. meansdisposed beyond said one supporting element in said given direction forrestraining said one supporting element against displacement in saidgiven direction; wherein the improvement comprises: c. avariable-opening bolster constituting said one supporting element andremovably received within said receptacle, said bolster comprising, incombination, i. a rigid frame dimensioned to fit within said receptacleof said tool container in abutting relation to the outlet face of saiddie and adapted to withstand extrusion pressure transmitted by said diein the direction of extrusion of said article; ii. first and secondgates mounted in said frame and cooperating therewith to define anopening in register with an aperture of said die, said gates havingfacing edges constituting opposite edges of said opening, each of saidgates having one face extending transversely of the direction ofextrusion and positioned to abut said outlet face of said die when saidframe is disposed in abutting relation thereto, said gates beingimmovable relative to said frame in the direction of extrusion but beingmovable within said frame toward and away from each other in a directiontransverse to the direction of extrusion for varying the size of saidopening, each of said gates having, in a side portion thereof, aninternally threaded bore extending in the direction of movement of saidgates, the bore of said first gate being axially aligned with the boreof said second gate and having an internal thread opposite in rotationalsense to the internal thread of the bore of said second gate; and iii.means accessible from the exterior of said tool container forsimultaneously moving said first and second gates as aforesaid inopposite directions and retaining said gates fixedly in any position towhich said gates are moved, said gate-moving means including at leastone rod rotatably journaled in said frame and extending through the boreof said first gate and the bore of said second gate aligned therewith,said rod having first and second externally threaded portionsrespectively engaging the internal threads of said bores, the externalthread of each of said rod portions corresponding in rotational sense tothe internal thread it engages, so that rotation of said rod effectssimultaneous oppositely directed translational movement of said firstand second gates.